Signaling system



y 7, 1942- M. c. SMITH 2,289,080

SIGNALING SYSTEM Filed Jan. so, 1941 F1" F y I Inventor:

- Mar-sden C. Smith,

- g' by H i His ttor'neg.

?atented .July 7, 1942 I SIGNALING SYSTEM Marsden (Jr-Smith, Richmond, Va., assignmto General Electric Company, a corporation of New I York Application January 3Q, 1941, Serial No. 376,587

9 Claims.

The present invention relates to signaling systerns and particularly to signaling systems such as are used-at street or highway intersections for controlling traific.

In traflic signaling systems, it is known to provide trafiic controlling signals at successive street intersections timed relatively to each other and to provide at a central point or station a master timer or controller for keeping the intersection signals in a desired timed relationship. In such systems, the mechanism at each intersection comprises an intersection timer or controller connected with suitable stop and go signals and is operated to display the stop and go signals in a desired sequence. In such signaling systems,

timed relation relatively to the other signals ofthe system, the intersection controller or timer which effects the operation of the signals at such intersection is actuated by the master controller to bring the stop and go=signals which itcontrols back into step with the other signals of the system." One arrangement utilized, for this purpose isthat of stopping the intersection controller and then starting it up at the correct time again to put the signals at the intersection in step with the other signals of the system.

In the operation of such systems, it may occur that when the signals at an intersection get out or" step with other signals in the system, they are so far out of step that it is necessary that the controller at such intersection be caused to efiect correction for a major portion of a signaling cycle. Heretoiore, as far as I am aware, it has been the practice to make the necessary correction to bring the signals at the intersection back into step during a single signaling cycle. This is undesirable as it means that one signaling period of-a cycle is prolonged unduly, a thing which may, especially in the case of heavy traffic along a highway, cause considerable disturbance. For example, it might happen that a major portion or an entire go period of a 'traflic signal cycle would be missed, a thing which in the case of heavy traflic might cause a considerable piling up of traflic on the highway.

The object of the present invention is to provide an improved construction and arrangement in a trafllc signaling system, whereby when the traflic signals at an intersection get out of step, they are'brought back into step by a certain limited amount at a time, the resynchronizing of should the signals at an intersection be out of step by 25 seconds then, according to my'invention, instead of correcting for this entire amount ample, three, which would mean correcting for 10 seconds on each of two successive traffic signaling cycles and correcting for 5 seconds inthethird cycle. An advantageous arrangement where the trafi'lc signals control traflic along a main thoroughfare, in so far as efiecting correction with v the least disturbance to tramc at the intersection, is to prolong the go signal on the main thoroughfare for the number of successive cycles required to bring the signals into step.

My invention is applicable to signaling systems of various types. In the present instance, I have elected to illustrate it in connection with a vtrafiic signaling system as disclosed in U. S. patent to R. A. Reid No. 2,236,298, issued March 25, 1941. It is to be understood, however, that while my invention is well adapted for'use in such a system, its use is by no means limited thereto as it may be used in connection with any specific type of signaling system to which it may be found ap plicable. I

For' 'a better understanding of my invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view of a trafiic control system embodying my invention, and Fig. 2 is a fragmentary diagram illustrating a modification of Fig. 1..

a cable l2, the return conductors being connected to a common ground terminal indicated between the two groups of signals. The specific signals herein illustrated comprise colored lenses with electric lamps positioned behind them, these signals being generally accepted by public authorities.

Each conductor of the cable J2 is connected directly or indirectly to a stationary contact I3 of asuitable controller and receives energy through a movable contact M from another stationary contact IS. The circuit for the lights continues to a suitable source through a conductor l9, closed switch contacts l1, IS, a conductor I9 and a suitable power switch 2|! to the source indicated merely by a plus sign. The contacts I5 are interconnected to the common supply conductor l6 so that when a movable bridging contact l4 rests on both of its pair of stationary contacts, it closes the circuit to the respective signal lamp in that circuit'to energize it.

The respective movable contacts 4 are moved by cams 2| one cam being provided for each movable contact. The cams are mounted on a common shaft 22 so that they may rotate in unison and their shapes are so arranged that certain ones of the contacts remain closed and certain ones of the contacts are opened in each of several predetermined positions of the shaft, a

complete cycle of operations being .performed in each revolution of the shaft.

The shaft 22 may contain cams for operating eration and the second being energized only when it is desired to stop the motor.

The keys 3|, 32 are placed in selected ones of the row of slots near the periphery of the dial. Five keys 3| and one key 32 are used. The keys 3| actuate a contact 39 mounted on a resilient supporting arm 39'. The arm 39 is rigidly mounted at one end and is provided on the underside of its free end with a suitable block which is positioned in the path of movement of the keys 3|. As the keys rotate, they successively engage the end of the block, momentarily contacts in circuits other than the signal circults. The shaft 22 carries one cam 23 used, for example, for operating contacts in a circuit arranged to maintain the shaft 22 in synchronism with a control dial. This circuit and its function will be explained later in the specification.

The shaft 22 with its group of cams is rotated step by step by a mechanism including a ratchet 'wheel 24 rigidly attached to the end of the shaft armature and pawl arm are raised to an upper being carried by the pivoted pawl arm, rotates the ratchet wheel 24, with the shaft 22 and thecams, to a new position. The ratchet wheel illustrated has six notches whereby six energizations of the coil 28 and the corresponding movements of the pawl will effect a complete revolution of the shaft and cams. It is evident, however,that any other desired number of notches may be used and any desired combination of the contact operations may be had in each position by suitably shaping the cams to effect the opening and closing of the circuits at these shaft positions.

The intermittent energization of the coil 28 is effected and timed by contacts actuated by a rotating dial 29 having two rows of slots near its periphery. Keys 3|, and 32 are placed in certain ones of the outer row of these slots so that at the proper instances during the rotation of the dial, they will actuate suitably positioned contacts to close the circuit to the coil 28 momentarily, each actuation effecting a movement of the shaft 22 to a succeeding position.

The dial 29 is mounted on a shaft 29-drlven by a motor 34 through the motor shaft 34' and a pair of gears 35, 36. The motor is preferably a synchronous motor whose armature speed is proportional to the frequency of the alternating current supplied to its operating field whereby the speed of the dial remains constant as long as the frequency of the supply current remains constant. The motor is provided with two opposing fields 31, 38, the first being used for normal opraise it and the contact 39 which is mounted on the arm 39 directly above the block, until the contact 39 engages a contact 49. The key 3| continues to rotate and passes beyond the block, after the two contacts have engaged, and the resilient arm returns the contact 39 to its original position thereby separating the contacts 39, 40 and breaking the circuit therethrough. The circuit closed by the engagement of the two contacts 39, 49 may be traced from the source at power switch 20, through a conductor 4| to the contacts 40, 39 through the resilient arm 39' to a conductor 42, to stationary contacts 43, 44, through a movable contact 45, conductors 46, 4'], switch 48 to coil 29 and to ground. There are five keys 3| in the dial 29 which provide for five energizations of the coil 28 during a single rotation of the dial 29. It is desirable, however to have the dial 29 make one complete revolution for each complete revolution of the shaft 22 and cams 2|, and it is further desirable to maintain a synchronous relationship between these two rotating bodies so that the dial may thereby become an indicator for the position of the cam shaft and the relative spacings between keys will be a criterion for the desired period lengths of a cycle. For effecting a sixth energization of the coil 29 in each revolution of the dial, the key 32 is provided. The key 32 is provided with a notch 32 so that this key will not actuate the contact 39. It will, however, actuate a second contact 49 to close a circuit to the coil 28. This contact 49 is mounted on a contact arm 49' which is in turn connected to the coil 28 through conductors 50, 41 and switch 48. The key 32 raises contact 49 into engagement with a stationary contact 5| which is connected to the current source at the power switch 20 through conductor 52, contacts I1, I 8, conductor l9 and power switch 20. Only one key 32 is used in the dial and there is, therefore, only one position of the dial at which this operation takes place. At the corresponding position of the cam shaft, the keys 3| are made ineffective to advance the cam shaft. The cam 23 on the shaft 22, provided for this purpose, opens the circuit through contacts 43, 44 at this position by lifting the movable contact 45. The normal circuit, through which the keys 3| advance the cam shaft, is thereby opened and the cam shaft 22 remains stationary until the key 32 is advanced by the dial to close the contacts 49, 5|. In this way, the cam shaft is advanced by keys 3| until it reaches this positionat which the cam 23 opens this circuit. It then remains stationary until the dial moves key 32 into position to actuate the contacts 49, 5|. The dial and cam shaft are then in the proper operating relationship. This; relationship exists during normal operation and involves no unnecessary delay in the advance of the cam shaft because key 32 being placed in a desired slot between two keys 3| functions exactly as a key 3| to advance the cam shaft to its next position at the proper instant of the operating cycle.

It is at times .desirable to advance the cam shaft by a hand-operated switch independently of the dial. If such operation is desired, the switch 48 is moved from its illustrated position to a second position in which it connects the coil 28 to a conductor 55. This conductor may be connected to the common current supply source by a hand-operated switch 56 and a conductor 51. When switch 48 is in this second position, therefore, the intermittent actuation of the switch 56 will advance the cam shaft 22.

It is also desirable at times to operate the signals' simply to indicate caution. For this purpose, the switch 58 is provided-having control of the contacts I1, l8 through which the current normally flows to the signals. When these contacts are separated, the common circuit to all the signals is interrupted and the normal sequential operation of the signals ceases. The switch 58 is further provided with movable contacts 59, 68. These contacts are respectively connected to the caution signals through conductors 6 I, 62 and for normal operation are in position to engage contacts 63, 64 connected to contacts 13 on the cam switch for sequential operation by cams on the shaft 22. For operating the caution signals alone, the switch 58-may be moved to a second position, thereby to move the contact 59 into engagement with a contact 65 and to move the contact 60 into engagement with a contact 66. Contacts 65, 66 are connected by a conductor 61 to a contact arm 68 pivotally mounted on a stationary block 69 and operable intermittently to open and close a pair of contacts 18, H. A star wheel 12 mounted on the motor shaft 34' actuates the contact arm 68. The contact II is connected to the common current source through a conductor l3, conductor l9 and power switch 28. When switch 58 is therefore moved to its second position, the signals of both groups l and H are deenergized by the separation of contacts l8' and only the amber or caution signals are energized through the newly closed contacts 59, 65 and 60, 66 and through the flashing device just described. When switch 58 is moved to its second position, the contacts I'l, |8 being separated, the key 32, upon actuation of the contact 49, cannot establish the circuit to the coil 28. The keys 3|, however, will continue to close the circuit to coil 28 until the cam shaft reaches the position at which this circuit is opened by contact 45.

the time required to place it into synchronism exceeds a predetermined value. The master controller used in this system is provided with a rotating cam 16 which rotates at the speed at which the secondary dials are intended to operate and is caused momentarily to actuate a switch ll once during each revolution. The switch 11 is connected between a current source and a common conductor i8. When ,the switch 11 is closed, current is fed to the respective controllers through conductor 18 and. branch conductors I3, 19a, 19b, etc. Branch conductors 19a, 19b, etc., lead to controllers at other intersections which controllers are in parallel with the one illustrated in detail and operate in a controller is connected to a resilient contact arm 88 having a contact 8| operable by a key 33 placed in the second row of slots in the dial 29. The arm 88 is placed next to the arm 49' and the key 33 is made longer than either key 3| or 32 so that it may engage the extended block .on the underside of the contact arm. At a predetermined position of the dial, the contact 8| is raised into engagement with a contact 82 and a circuit is established to the braking field 38 on the motor 35 through a conductor 83, a switch 84 and a conductor 85. Only one key 33 is used so that one actuation of the contact 8| is obtained at each revolution of the dial 29. If at the instant at which the contact 8| engages the contact 82 the master controller-switch I1 is closed and current is fed to the braking field 38, the motor stops until such time as the master cam I6 opens the switch 11. At that instant, the braking coil 38 becomes deenergized. The key 33 moves beyond the actuating block of the contact 85 and the circuit is opened.

As previously stated, it is possible for the secondary controller to be out of step with the master timer by a period equalling the greater portion of an operating cycle. To bring the controller into synchronism, it would be necessary in the systems heretofore used, to hold it stationary similar manner. Conductor 19 in the described contacts 8 l, 82.

for this comparatively long period of time and that would result in an undesirable delay of trafiic. A time limiting switch is, therefore, provided in the braking coil circuit to release the timer after a predetermined shortperiod of time,

thereby enabling it to operate for one complete cycle before it is again stopped due to its being out of synchronism. The timer 'is stopped through successive cycles, for this period of time as determined by the time limiting switch, until the timer is brought into synchronism. In the latter case, the brakingcoil circuit is opened by the master timer at the instant at which syn-.

chronism is reached and the time limiting switch merely returns to normal condition ready for an operation at a subsequent period. To carry out this operation, any suitable time delay switch may be used. In the present case, a simple dashpot delayed switch is illustrated. When current flows to the braking field 38, it flows through the switch 84, which preferably comprises a stationary contact 86 and a cooperating switch ele-. ment 81. Current also flows through a coil 88 provided with a switch actuating armature 89 and connected between the conducto'r'85 and ground. Current flows through, this switch coil only when the master controller switch 11' and the contacts 8|, 82 are closed. If current flows through, the coil 88 for a predetermined time, it raises the armature 89 against the action of a dash-pot delay mechanism 98 to open the switch 84 and thereby break the circuit between conductors 83. and 85. This operation deenergizes the field 38 and permits the motor 34 to rotate the dial sufficiently to' break the circuit at the The dial will then rotate for another complete revolution, still out'of synchronism with the other controllers but by a smaller amount, until its key 33 again closes the circuit through contacts 8|, 82. If the master switch 11 is then opened within the period set for the switch '84, there will be no operation of the time delay switch 84, the dial will continue operation in synchronism with the master timer and the armature 89 will merely return to its starting position.

In operation of the above system, each tramc this purpose, which closes a circuit from the common source at switch 20 through conductor 4| conductor 93, switch 92 and conductor 94. A closure of the switch 28 then provides current for the signaling circuits and a movement of switch 48, to the position shown, prepares the controller for automatic operation. The motor then drives the dial 29 and the keys 3| actuate the contact 39 thereby effecting a rotation of the shaft 22 up to the position at which cam 23.0pens the circuit established by the keys 3| and contact 39. The drum will then'remain stationary until the dial moves to the position at which the key 32 vactuates the contact 49. The shaft 22 and the dial 29 are then in synchronism with each other. During this operation the key 33 also moves with the dial and in each, revolution of the dial it closes the circuit to the braking field 38 by the closure of contacts 8|, 82. II the dial is in synchronism with the master timer, the switch II will be opened at that same instant and nothing happens. If the dial is out of synchronism with the master, the dial will be stopped or at least slowed down until it is released either by the opening of the master controller switch 11 or by the opening of the time delay switch 84.

If the time period required to place this dial in synchronism with the master timer is greater than the time limit for which the switch '84 is set, the switch 84 will open the circuit to the braking coil 38, the dial will begin to move and will open the braking coil circuit at the contacts ll, 82; The dial will then continue for a complete revolution during which the switch 84 returns to normal closed position, At the next actuation ofthe contacts 8|, 82, the braking coil will again be energized and the time delay switch 84 will again begin its timing. If the dial 29 comes into synchronous relationship with the.

master timerrbefore the switch 84 operates,' the master switch 11 will be opened, the braking coil 38 will be deenergized and the dial 29 will again begin .to rotate. The key 33 again opens the braking coil circuit at contacts 8|, 82 so that up on a reclosure of the master switch 11, the braking coil 38 remains deenergized. The number of cycles over which this operation is distributed is dependent upon the time for which the time delay switch 84 is set and upon the period by which the controller is out of step with the master controller. A period of ten seconds has been found satisfactory in one installation but any other period may be used, dependent upon the traillc conditions existing at an intersection.

The position of the key 33 in the dial is determined by the progression timing of the controller relative to the other controllers in the system. Because of this timing requirement it may happen that the dial is held up during a signal period other than the main street green period.

It has been found in practice however that in the main street green period and cause little disturbance in trafllc flow when they fall in signal periods other than the main street green period.

Fig. 2 is a fragmentary diagram disclosing a modification of the diagram of Fig. 1. The modification is essentially the provision of a local source of current for the energization of the time delay relay and the motor brake coils. Referring to this diagram in detail, a relay 95 provided with a coil 96, an armature 9 1 and a movable contact 98 is connected into the circuit of the synchronizing conductor 83. When energy flows throughthis conductor 83 in accordance with the operations described in connection with Fig. 1, current also flows through the contacts 86, 81, conductor 85, through the coil 96 to ground. The relay contact 98 is thereby operated to close a circuit between a conductor 99 and a conductor I90. The conductor 99 is connected to a local source of current at the location of the specific intersection controller which is to be synchronized. The conductor Hill is connected to the brake coil 38. Another conductor |9l leads from conductor I00 to the time delay relay coil 88 and from there to ground. In operation, therefore, the circuit between conductors 99 and I90 is closed immediately upon energization of the conductor 83. The brake coil 38 is thereby energized, and the time delay coil, being energized, immediately tends to lift its armature 89 against the delaying action imposed upon it by the dash-pot 90. If the period of energization of the conductor 83 is longer than the time period for which the dash-pot 90 is set, the circuit to the relay coil 96 is broken by the separation of contacts 86, 81. The brake coil 38 is thereby momentarily deenergized and the motor 34 moves the key 33 so as to open the circuit to conductor 83. The relay coil 96 is thereupon deenergized and opens the circuit to both coils 38 and 88. The time delay relay coil 88 being deenergized, the armature 89 returns to initial position and the contacts 86 and 81 reclose to be in position for a succeeding operation at the next resynchronizing instant in the succeeding operating cycle of the trafiic signal controller.

What I claim as new and desire to secure by' Letters Patent of the United States is:

1.- In a signal system, the combination of a master controller operating upon a predetermined cycle of operations, a secondary controller, means for continuously operating said secondary controller through a predetermined cycle of operatiOns corresponding to the master controller operating cycle, braking means in said secondary controller operable to delay said controller, means operated by said secondary controller at a predetermined position during its cyclic operation to actuate said braking means, means operated by said master controller for releasing said braking means when it reaches synchronism with said secondary controller, and means operated to effeet the release of said braking means ahead of said. master controller release operation if the time period of said brake actuation exceeds a predetermined period.

. 2. In a traflic signal system, the combination of a master controller, a secondary controller,

means for continuously operating said master and secondary controllers through predetermined corresponding cycles of operations, braking means in said secondary controller, means operated by said secondary controller at a predetermined instant during its operating cycle to energize said braking means, means operated by said master controller at a predetermined corresponding instant in its operating cycle for deenergizing said braking means, and means in said secondary controller operated t9 deenergize said braking means ahead of said master controller operation if the time of energization of said braking means is greater than a predetermined period.

3. In a traiiic signaling system, the combination of a master controller and a secondary controller each of said controllers being operable through predetermined and corresponding cyclic operations, means -for stopping said secondary controller, means operated by said secondary controller for efiecting an operation of said stopping means at a predetermined instant in each cycle of operation, means in said master controller for efiecting a release operation of said stopping means at a predetermined corresponding instant in its cycle of operation, and means in said secondary controller operated to effect a release operation of said stopping means if said master controller does not efiect a release operation of said stopping means within a predetermined period of time.

4. In a trafiic signaling system, the combination of a master controller and a secondary controller, each of said controllers being operable through corresponding cyclic operations, means for stopping said secondary controller, means operated by said secondary controller for energizing said stopping means at a predetermined instant in its cycle of operation. means in said master controller for deenergizing said stopping means at a predetermined instant in its corresponding cycle of operation, and means in said secondary controller operated to deenergize said stopping means if said master controller does not deenergize said stopping means within a predetermined maximum period of time.

5. In a trafflc signal control system, the combination of a master controller, a series of secondary controllers each of said secondary controllers being provided with a braking coil arranged to be energized at a predetermined point in its respective operating cycle, a common conductor normally energized and connected to said secondary controllers to energize said braking coils when the circuits thereto are closed by said controllers respectively, means in said master controller for momentarily deenergizing said common conductor when it comes into M- chronism with the secondary controllers thereby deenergizing said braking coils and effecting an operation of said controllers to break their respective connections to said common conductor, and a time-limiting switch connectedbetween termined positions during its operation to energize said braking means, means operated by said master controller for deenergizing said braking means at a predetermined instant during its own operating cycle, and a dash-pot relay in the circuit of said braking means in said secondary controller operable to deenergize said braking rentand an instantly actuating relay operated by said secondary controller at predetermined positions during its operation to energize said braking means, means for operating said master controller through a cycle of operations corresponding to the cycle of operations of said secondary controller, means operated by said master controller for deenergizing said braking means when said master controller comes to synchronism with said secondary controller, and a time delay switch in the circuit of said braking means insaid secondary controller operable to deenergize said instantaneously operating relay and said common conductor and said braking coil in each of said controllers to deenergize said braking coil within a predetermined time interval whereby the secondary controller operates through another cycle and is again stopped, this operation being repeated until synchronous relationship with the master controller is established.

6. In a traflic signal system, the combination of cycle, a secondary controller, means for conthereby to deenergize said braking means within a predetermined time period after the operation of said brake energizing means in said secondary -controller. I

8. In a signal system, the combination of a master controller and a secondary controller operable respectively through signal cycles of corresponding lengths, means operated by said secondary controller at a predetermined instant in each operating cycle to stop said secondary controller, meansin said master controller to restart said secondary controller at a corresponding instant in-its operating cycle, and means in said secondary controller to restart said secondary controller prior to the restarting instant ofsaid master controller if the time period between said stopping instant and said master re-- start instant exceeds a predetermined maximum.

9. In a signal system, the combination of a -master controller and a secondary controller operable through corresponding signal cycles,

-a master controller operating at a predetermined tinuously operating said secondary controller through a predetermined cycle of operations corresponding to the master controller cycle, braking means in said secondary controller, means operated by said secondary controller at predemeans operated by said secondary controller at a predetermined instant in each operating cycle to stop said secondary controller, means in said master controller to restart said secondary controller at the instant at which the master controller comes into synchronism with the secondary controller, and means in said secondary controller to restart it prior to the restarting instant of said master controller if the time period between said stopping instant and said instant oi synchronization exceeds a predetermined maximum.

MARSDEN C. SMITH. 

